Tactile Turn Bolt Action Pen in machined titanium, Standard 5.6" (10-BA1-TTM-TTM). Official listing is titanium with an all-metal bolt-action mechanism and a stainless steel deep-carry clip. Official specs: 0.43" diameter, 5.6" long, 1.3 oz, Pilot G2 0.7mm refill. Official page lists titanium as durable, lightweight, and corrosion resistant. Machined in Dallas, TX. Specs from the tactileturn.com Titanium Bolt Action Pen page.
Machined titanium Standard. The 5.6" Bolt Action with a Euro-style G2 refill.